Gun sight



March 17, 1942 E. E. GREG-CRY GUN SIGHT 2 Sheets-Sheet Filed March 27,1959 March 17, 1942. E. E. GREGORY I 2,276,270

GUN SIGHT Filed March 2 7, 19:59 2 Sheets-Sheet 2 Patented Mar. 17, 1942UNITED STATES PATENT OFFICE v GUN SIGHT Eli n. Gregory, Stirling, NJJ'.Application March 27, 1939, Serial No. 264,283

4Claims.

This invention relates to gun sights, and in particular to certain newand useful improvements in range-finding binocular gun sights.

An object of this invention is to increasethe useful range-findingefiect of binocular gun sights of the type disclosed in my LettersPatent No. 1,350,153 and No. 1,476,884. A further object of thisinvention is to provide an efiective rangefinding sight, automatic inoperation, and simple and rugged in construction, by which a machinegunner, for example, without any adjustment of his sights, can instantlytrain his weapon on a target appearing suddenly at an unknown range.

For a consideration of what I believe to be novel in my invention,attention is directed to the accompanying description and the claimsappended hereto. The invention is illustrated, by way of example, in theaccompanying drawi s in which- Fig. 1 is a schematic diagram of theoperation of my invention at the comparatively long range R:

Fig. 2 shows the optical cross" formed by the use of my invention atrange R;

Fig. 3 is a schematic diagram of the operation of my invention at theshorter range 1';

Fig. 4 shows the optical cross formed by the use of my invention atrange r;

Fig. 5 is a side elevation of a machine gun provided with my invention;

Fig. 6 is a plan view of the machine gun provided with my invention;

Fig. 7 is a front elevation of a machine gun provided with my invention;

Fig. 8 is a horizontal section of the rear sighting'member onlydisclosing an alternative construction; and

Fig. 9 is a front elevation of a portion of a gun shield embodying amodified form of the front sighting element of my invention.

The operation of my invention will be'understood from a study of theschematic drawings, Figs. 1 through 4. In Fig. 1 we see a target I at arange R from the observer t. The dot-anddash lines show lines of sightfrom the eyes of v the observer t passing by means of a train of fixedmirrors 3 past the sighting wires 2 to the target i and forming anapparent optical cross near the base of the sighting wires 2. Theappearance of these wires, when the eyes of the observer 4 are focusedon the target I, is shown in Fig. 2. Each wire 2 is seen by one eye onlyof the observer and, therefore, an optical cross 5 consisting of anopaque spot is formed where the v to intersect near their tops.

separate images of wires 2 apparently cross. At the range R the lines ofsight from the mirror train 3 to the target I pass through the sightingwires 2 near their base.

Fig. 3 shows the target 1 at a shorter range T 1 from the observer 4.The lines of sight from the observer 4 to the target-i pass by way ofthe train of fixed mirrors 3 past the sighting wires 2 as they did whenthe target was at the longer range R, except that sighting wires 2 nowappear The appearance of the sighting wires 2 to the observer 4 whensight ing at the range 1' is shown in Fig. 4. An optical cross 5 isformed by the apparent intersection of wires 2 as it was when the sightwas employed at the range R, except that opaque spot 5 is near the topof said wires 2.

The purpose of the interposition of the mirror train 3 in the lines ofvision from the eyes t of the user past the sighting wires 2 to thetarget I is to increase the apparent vertical shift of the opaque spot 5for a given change in range. I have found that by increasing thedistance apart of the sighting wires 2 and by use of a device toincrease proportionately the effective inter-pupilary distance of theeyes 4 of the user, such as the mirror train 3, the efiectiveness of thewires 2 as a means of forming an optical cross is greatly increased.That is, the sensitivity of the automatic rangefinding efiect of thisdevice to changes in range is greater, particularly at larger ranges,and a fixed rear sighting element is provided, which has hiterto beenlacking in optical cross sights.

In Figs. 5 through 7 Ishow in detail a preferable construction of adevice embodying my invention. I show a machine gun H) on which ismounted rigidly, at right angles to the axis of the barrel II, and atthe rear of the weapon ID, a sighting element consisting of a sight tubeI in which are afiixed two parallel eye-pieces B with their axesseparated by the average interpupilary distance of the human eyes andequidistant from the center of said sight tube i. Eye-pieces 6 may bemade adjustable for individual differences and consist simply of tubesopening into sight tube 1 and affixed thereto preferably by light-tightconnections. The axes of eye-pieces 6 are parallel to the axis of barrelH, and perpendicular to the axis of sight tube 1.

At the front of weapon H! is mounted a support 9, parallel to sight tubeI holding in its ends two sighting wires 8 in such a manner that theplane .of the axes of eye-pieces 6 intersects said sighting wires 8approximately midway from top to bottom thereof. Said sighting wires 8are of the shape and function of the wires 2 in Figs. 2 and 4.

In Fig. 6 the rear sighting element is shown partly in cross-section,revealing its internal construction. It consists of (a) a tube 1,preferably light-tight, having two openings I 4 located at the extremeopposite ends of tube i and on the front side thereof, and having twoeye-pieces 6 mounted as hereinbefore described; (1)) two fixed prismaticmirrors i2 mounted within tube I with their respective reflectingsurfaces mutually perpendicular, and arranged insuch a manner. as toreflect, along paths parallel to the axis of said tube 1 and with theright and left lines separated by 180 directionally, the lines of visionentering the two eye-pieces' 6; (c) two fixed prismatic mirrors l3mountedwithin tube 7 with their respective reflecting surfaces mutuallyperpendicular, and arranged in such a manner as to reflect,

toward the front of the weapon l along paths perpendicular to the axisof tube I and in the plane of the axis of eye-pieces 6 the lines ofvision coming from the mirrors I2 parallel to the axis of tube 7.

The rear sighting element consists essentially of two equally opposedoptical trains, one right and one left, each consisting of an eye-piece6, a fixed prismatic mirror i2, and another fixed prismatic mirror i3.These elements are mounted in a tube 3 substantially as described and soarranged that parallel beanis of light entering the eye pieces 8 arereflected along paths parallel to the entering path but separated by thedistance from right mirror i3 to left mirror l3. Further, the rearsighting element is preferably constructed to permit light to enter onlyby the openings M and the eye-pieces 6. Thus, when an observer looksinto the eye-pieces 6, he views the scene before him as if his eyes wereseparated by the distance from the left mirror i3 to the right mirrorI3, and the sighting wires 8 interposed in his line of vision cooperateto form an optical cross which shifts its bead with changes in range asheretofore described and illustrated in Figs. 1 through 4.

Fig. 8 shows a modified construction of the rear sighting elementemploying plane mirrors 15 instead of prismatic mirrors l2 and planemirrors H5 in place of prismatic mirrors l3.

Fig. 9 shows a modified construction of the front sighting element inwhich the optical cross forming devices 8a constitute a part of aprotective shield 21. This shield 2| may be of any desired form orpattern, the operative part thereof for the purposes of this inventionbeing the front sighting shapes 8a which, by means of the rear sightingelement heretofore disclosed form the optical cross constituting the.bead to be placed on the target. In the portion of the for the purposeof disclosing the spirit, scope, and

operation thereof, but not intended as a limitation thereof. While Ihave described my invention as applied to a machine gun it is to beunderstood that it may be applied to any object to be aimed, "as, forexample, an airplane carrying fixed guns. Moreover, although I havedescribed my invention as embodied in a sight of portable size, usefulon small arms, it is no departure from the invention herein disclosed toconstruct a sight employing any practicable dimensions, for example,mounting the prismatic mirrors l3 and the sighting wires 8 in thedisclosed relationship protective shield shown in Fig. 9, the lines ofvision from the user to the target pass the devices 8a through theapertures 22. This is the preferred construction of a gun shieldembodying my invention, but the devices 8a may be shaped to each otherand to the eye-pieces 6 and prismatic mirrors I2 on the left and rightwing tips of an airplane. It will be understood that these and otherchanges may be made within the scope of my invention as setforth in theappended claims.

I claim:

l. A binocular sight for an instrument to be aimed comprising a pair ofeye-pieces, reflecting means aligned with each of said eye-pieces, asecond reflecting means positioned transversely and outwardly of theline of vision through each of said eye-pieces, said second reflectingmeans being spaced apart a distance substantially greater than saideye-pieces, said first mentioned and said second mentioned reflectingmeans being so positioned with respect to one another and to saideye-pieces that said second mentioned reflecting means is,

adapted to reflect images onto said first mentioned reflecting means.and said first mentioned reflecting means is adapted to reflect suchimages impinging thereon through said eye-pieces, and a sighting elementpositioned in alignment with each of said second reflecting means, andat the opposite side of said reflecting means from said eye-pieces, saidsighting elements being spaced apart a distance substantially equal tothe spacing of said second reflecting means and converging upwardly,said sighting elements, when an object beyond said sighting elementsaimed at is .viewed by a person with botheyes, producing the opticalefiect of crossing one another at varying points, depending on thedistance ofsaid object from the person doing the aiming.

2. A binocular gun sight comprising a pair of eye-pieces,reflectingmeans aligned with each of said eye-pieces, a secondreflecting means positioned transversely and outwardly of the line ofvision through each of said eye-pieces, said second reflecting meansbeing spaced apart a distance substantially greater than said eyepieces,said first mentioned and said second mentioned reflecting means being sopositioned with respect to one another and to said eye-pieces that saidsecond mentioned reflecting-means is adapted to reflect images onto saidfirst mentioned reflecting means and said first mentioned reflectingmeans is adapted to reflect such images impinging thereon through saideye-pieces,

with each of said second reflecting means, and at the opposite side ofsaid reflecting means from said eye-pieces, said sighting elements itbeing spaced apart a distance substantially equal to the spacing of saidsecond reflecting means and converging upwardly, but not intersectingwithin the area visible through said eye-pieces by means of saidreflecting-means, said sighting elements, when an object beyond saidsighting elements aimed at is viewed by a person with both eyes,producing the optical effect of crossing one another at varying verticalpoints, depending on the distance of said object from the person doingthe aiming.

3. A binocular gun sight comprising a pair of eye-pieces, reflectingmeans aligned with each of said eye-pieces, a second reflecting meanspositioned transversely and outwardly of the line of vision through eachof said eye-pieces, said second reflecting means being spaced apart adistance substantially greater than said eye-pieces, said firstmentioned and said second mentioned reflecting means being so positionedwith respect to one another and to said eye-pieces that said secondmentioned reflecting means is adapted to reflect images onto said firstmentioned reflecting means and said first mentioned reflecting means isadapted to -reflect such images impinging thereon through saideye-pieces, and a sighting wire positioned in alignment with each offleeting means, said sighting wires, whenan object beyond said sightingwires aimed at is viewed by a person with both eyes, producing theoptical eflect of crossing one another at varying vertical points,depending on the distance of said object from the person doing theaiming.

4. A binocular gun sight comprising a pair of eye-pieces, reflectingmeans aligned with each 10 of said eye-pieces, a second reflecting meanspositioned transversely and outwardly of the line of vision through eachof said eye-pieces, said second reflecting means being spaced apart adistance substantially greater than said eye- 5 pieces, said firstmentioned and said second men tioned reflecting means being sopositioned with respect to one another and to said eye-pieces that saidsecond mentioned reflecting means is adapted to reflect images onto saidfirst men- 20 tioned reflecting means and said first mentionedreflecting means is adapted to reflect such images impinging thereonthrough said eye-pieces, and a sighting wire positioned in alignmentwith each of said second reflecting means and at the 25 opposite side ofsaid reflecting means from said eye-pieces, said sighting wires beingspaced apart a distance substantially equal to the spacing of saidsecond reflecting means and each curving upwardly and inwardly, but notintersecting 30 within the area visible through said eye-pieces by meansof said reflecting means, said sighting wires, when an object beyondsaid sighting wires aimed at is viewed by a person with both eyes.producing the optical eflect of crossing one an- BB'other at varyingvertical points, depending on the distance of said object from theperson doing the aiming.

ELI E. GREGORY.

